The present invention relates to a reproducing apparatus for a DVCR (digital video cassette recorder) having a reverse operation function and, more particularly, to a reproducing apparatus for a DVCR which is capable of reverse playback of data by reversing the rotation direction of the head as well as the traveling direction of the tape.
Generally, the traveling direction of the tape and the rotation of the drum are performed in the same direction only (unidirectionally) in playing a DVCR. FIG. 1 shows the tape traveling direction and video head rotation direction in reading data recorded on the tape. In this drawing, the traveling direction of the tape and the rotation direction of the drum are designed to be the same (unidirectional) so that the rotation of the video head is always performed upward from the bottom of the tape.
Meanwhile, FIG. 2 is a block diagram of a sync signal detector for detecting a sync signal when the rotation direction of the drum and the traveling direction of the tape are the same (unidirectional). There are two types of sync signal detection, that is, parallel and serial sync signal detections. Here, only the parallel sync signal will be explained with reference to U.S. Pat. No. 4,879,731.
Like the serial sync signal detection, in the parallel mode, a serial clock Sclk and serial data Sdata are received to form a parallel clock Pclk and parallel data Pdata via a serial/parallel converter 1.
The parallel data and parallel clock are compared with a predetermined sync pattern by detector 2 and comparator 3, thereby detecting a sync signal. Here, the procedure for comparing the sync pattern with the parallel data is different from that of the serial mode. This is because M-N modulation/demodulation requires N comparators, and a sync signal detected from the N comparators becomes the final form of the sync signal and re-arranged data using an encoder and decoder.
As to the comparison result, if a slip occurs before or after the position where the sync signal is detected, a signal SYNC-IN-WINDOW is moved using first and third signal generators 4 and 6. If the sync signal is produced within the signal SYNC-IN-WINDOW, this is regarded as being actual. In other cases, it is regarded that the sync signal is detected falsely.
Meanwhile, in the prior art DVCR, the video head rotation direction and tape traveling direction are unidirectional so that only forward data playback, but not reverse data playback, is enabled.